Thin film magnetic head with coil windings receiving trench

ABSTRACT

A thin film magnetic head having a substrate, magnetic head components and a superstrate formed of materials which are highly resistive to being abraded by a magnetic media being moved thereacross is shown. The magnetic head includes a magnetic bottom pole piece having a front gap section and a rearward extending portion. A lateral wall layer formed of a magnetic material and of predetermined thickness, has a forward wall section and a rearward wall section which define a coil windings receiving trench adjacent the front gap section of the bottom pole piece layer. The bottom pole piece forms a bottom enclosure for the coil windings receiving trench. A coil having coil windings is formed on the bottom pole piece and the coil windings thickness is less than the thickness of the lateral wall layer. An insulating structure having a thin gap defining section is located in the transducing gap and a thick coil windings enclosing portion is located in the coil winding receiving trench formed between sections in the lateral wall layer. The thin gap defining portion establishes the thickness of a magnetic transducing gap and the thick coil windings enclosing portion encloses that portion of the coil windings located in the coil windings receiving trench. A magnetic top pole piece layer, including a contoured outer surface having a step formed therein, bridges from the forward wall section to a rearward wall section to enclose the coil windings receiving trench.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a thin film magnetic head formed on asubstrate having top and bottom pole pieces, coil windings and asuperstrate, and more particularly relates to a thin film magnetic tapehead assembly which includes a lateral wall layer formed of a magneticmaterial which defines a coil windings receiving trench enclosed by thetop pole piece and bottom pole piece. An insulating structure is formedbetween the lateral wall layer and the top pole piece. The insulatingstructure has a thin gap defining portion for establishing the thicknessof a magnetic transducing gap between the top pole piece and bottom poleand a thick coil windings enclosing portion which encapsulates thatportion of the coil windings located in the coil windings receivingtrench formed in the lateral wall layer. In another embodiment, aleveler layer is formed on the top pole piece and a rearward levelersection located on that portion of the insulating structure extendingrearwardly on the rearwardly extending portion of the bottom pole piece,from a rear magnetic closure section. A superstrate is placed onto theleveler layer to enclose the contoured outer surface of the top polepiece. The thin film magnetic tape head assembly defines a tape guidingsurface that is highly resistant to being abraded by a magnetic tapebeing moved thereacross.

2. Description of the Prior Art.

It is well known in the art to form a thin film magnetic head on asubstrate wherein the magnetic head comprises a substrate, top andbottom pole pieces, a coil having multiple windings which may be stackedor located between the pole pieces. A typical thin film head of thisstructure is illustrated in FIG. 1. of the drawing, and is labeled as"Prior Art". In FIG. 1, the substrate 30 has a deposited bottom polepiece 32 which is relatively planar in shape, and one end thereof, frontgap section 34, which defines one side of a transducing gap 40. Adeposited planarized coil having a plurality of coil windings, showngenerally as 42, is encapsulated in an insulating layer 44. A portion ofthe insulating layer 44 defines the thickness of the transducing gap 40.A deposited top pole piece 46 located on the insulating layer 44 has afront gap section 48 that defines the other side of the transducing gap40 and the other end is contiguous the rearwardly extending portion ofthe bottom pole piece to form a rear magnetic closure section 49. Anovercoat layer 50, formed of a material that will conform to thecontoured stepped outer surface 52, is deposited on the top pole piece46. An adhesive or filler layer 58 is then applied over the overcoatlayer 50 to form a relatively planar surface for supporting asuperstrate 59. A magnetic tape, shown as tape 54, is transported acrossthe thin film magnetic head to coact with the magnetic pole pieces 32and 46 and the transducing gap 40.

EPO Publication No. 0 051 123 discloses a magnetic transducer having topand bottom substrates formed of a magnetic material, which function asthe pole piece, with a deposited thin film coil between the pole pieces.

In another known prior art, a ferrite magnetic head illustrated in FIG.2, has a thick magnetic pole piece 60, formed of a ferrite material,which has a slot 62 formed therein and which is filled with a glassmaterial 64. The glass material 64 placed in the slot 62 functions toreceive and support a spiral coil having coil windings 66, which are, inturn, encapsulated in an insulating structure 74. The combination of theslot, glass and coil windings function to physically impose a separationbetween the pole pieces. As shown in FIG. 2, the thick ferrite polepiece 60 has one end 70 thereof defining one side of a transducing gap72, which gap is filled by an insulating material 68 which is part of aninsulating layer 74. A top pole piece 76, which typically is a depositedmagnetic layer, has one end thereof, end 78, defining the other side ofthe transducing gap 72. Also, a rear magnetic closure section 88 isformed rearward of the transducing gap. A protective overcoat layer 80formed of a material that will conform to the contoured stepped outersurface of the top pole piece 76, is deposited onto the top pole piece76. An adhesive or filler layer 81 is then applied over the overcoatlayer 50 to form a relatively planar surface to receive a superstrate86. A magnetic tape 84 is transported across the tape engaging surface86 of the thin film magnetic head.

One specific prior art thin film magnetic head using this structure isdisclosed in U.S. Pat. No. 4,490,760 to Kaminaka et al. U.S. Pat. No.4,490,760 also discloses use of a glass filled slot on the mediaengaging surface.

A thin film head having a glass filled slot, similar to that disclosedin U.S. Pat. No. 4,490,760, is discussed in an article captioned "HighTrack Density Thin-Film Tape Heads" which appeared in the IEEETransactions on Magnetics, Volume Mag-15, No. 3, July 1979 at pages 1130through 1134, wherein the authors are Kenji Kanai, Nobuyuki Kaminaka,Norimoto Nouchi, Noboru Nomura and Eiichi Hirota (the "Kanai et al.Publication"). In the Kanai et al. Publication, reference is made toFIG. 2 thereof which shows a protective cover placed over a contouredpole piece exposing an area adjacent the transducing portion "A" of thetop pole piece. This is referred to as a "large step structure". Asnoted in the Kanai et al. Publication, a "large step structure" isundesirable.

The Kanai et al. Publication also teaches the concept of a slot beingformed in the bottom pole piece, and filling the same with glass. Thisresults in effectively separating the bottom pole piece from the toppole piece. A deposited thin film coil is formed on the glass filledslot. A top pole piece is then deposited onto the thin film coil. Thisresult is a "small step" in the region between the protective layer andthe transducing portion "A" of the top magnetic layer. The effect of the"small step" is to reduce the undesirable surface area which forms aportion of the tape engaging surface. This is shown in FIG. 4 of theKanai et al. Publication.

As is readily apparent from the Prior Art thin film magnetic headassemblies of FIGS. 1 and 2, the magnetic media engaging surface isformed of a plurality of different materials that are subjected to beingabraded by the moving magnetic media. It is well known in the art thatdifferent materials, when abraded by a magnetic media being transportedthereacross, abrade at different rates. In magnetic tape heads, unevenabrading of materials due to a magnetic tape being transportedthereacross can result in the formation of grooves at various materialboundaries, or otherwise result in the flaking off or smearing of theabraded material along the tape engaging surface.

U.S. Pat. No. 4,422,117 discloses a thin film head having a glass filledslot in the bottom pole piece for supporting a deposited thin film coil.A thin film pole piece is then deposited onto the deposited coil. Asuperstrate is applied to the contoured top pole piece by means of glassbonding. This results in glass being located on, and forming part of,the tape engaging surface between the superstrate and the contoured toppole piece.

U.S. Pat. No. 4,396,967 discloses a deposited thin film head whereinglass filled slots are formed in a thin ferrite layer affixed to anon-magnetic Barium Titanate Ceramic (BTC) support piece defining oneside of a magnetic head structure. A thin ferrite layer is formed on asecond BTC support piece which defines the other side of the magnetichead structure. The other BTC support piece has individual coil windingslots formed therein, which, in turn, contain individual coil windings.When the two BTC support pieces are assembled, the glass filled slotsmate with the ferrite containing the coil windings in the slot such thatthe coil windings are enclosed by, and recessed within, the thin ferritelayer. In this structure, the two thin ferrite layers form part of themedia engaging surface in the vicinity of the transducing gap.

SUMMARY OF THE PRESENT INVENTION

The present invention relates to a new and novel thin film magnetic tapehead assembly wherein the magnetic pole pieces are both formed ofdeposited layers of magnetic material and wherein the coil windings,forming a coil for the head assembly, are integrated within the headstructure such that the magnetic pole pieces and other differentmaterials that typically are subject to being abraded by a magnetic tapebeing transported across the tape engaging surface of the head assemblyhave the wearing thereof minimized due to the tape engaging surface anhaving an improved resistance to being abraded by the magnetic tape. Theso formed thin film magnetic tape head has greatly improved wearcharacteristics so that life of the thin film magnetic tape head isincreased.

The thin film magnetic tape head assembly of the present inventionincludes a substrate having a deposition surface and an end surfacewhich is substantially perpendicular to the deposition surface. Thesubstrate is formed of a material which is highly resistive to beingabraded by a magnetic tape being moved thereacross. The substrate has atape engaging surface defined at a predetermined position on the endsurface thereof. A magnetic bottom pole piece layer is located on thedeposition surface of the substrate, and the bottom pole piece layer hasa front gap section and a rearwardly extending portion. The front gapsection thereof is positioned adjacent the end of the substrate definingthe tape engaging surface. The rearwardly extending portion of the themagnetic bottom pole piece is located rearward of and in a spacedopposed relationship from the front gap section and from the tapeengaging surface. A lateral wall layer, formed of a magnetic material,has a forward wall section and a rearward wall section defining a coilwindings receiving trench therebetween. The lateral wall layer is formedof predetermined thickness and is positioned on the bottom pole piecelayer. The forward wall section is positioned contiguous the front gapsection of the bottom pole piece layer, establishing the front wallsection as one side of a magnetic transducing gap. The rearward wallsection is positioned a predetermined distance rearward from the frontwall section and contiguous the rearwardly extending portion of thebottom pole piece layer forming one side of a rear magnetic closuresection. The bottom pole piece forms a bottom enclosure for the coilwindings receiving trench.

A coil, which in the preferred embodiment is a multiplanar coil, havinga plurality of coil windings is formed on the bottom pole piece. Thecoil has a portion of the coil windings located between the top polepiece and the bottom pole piece and the remaining portion thereofextends on the rearward portion on the bottom pole piece.

An insulating structure has a thin gap defining portion and a thick coilwindings enclosing portion. The thin gap defining portion of theinsulating structure is formed of predetermined thickness and is locatedbetween the front gap section of the top pole piece and the bottom polepiece to establish the thickness of the magnetic transducing gap. Thethick coil windings enclosing portion is positioned to enclose andsurround that portion of the coil windings enclosed between the top polepiece and the bottom pole piece.

A magnetic top pole piece layer having a front gap section and a stepformed in the contoured outer surface is positioned on the insulatingstructure with the bottom surface thereof extending from the front gapsection to the rear magnetic closure section on the rearwardly extendingportion of the bottom pole piece. The top pole piece forms a topenclosure for the coil windings and the the bottom pole piece layerforms the bottom enclosure. The media engaging edge of the top polepiece is located adjacent the front gap section of the bottom pole pieceand is in spaced opposed parallel relationship with the media engagingsurface of the bottom pole piece to define a transverse tape engagingsurface thereacross.

A leveler layer, having a thickness which is slightly greater than the"step" of the top pole piece, is formed on the top pole piece layer.

The "step" of the top pole piece generally refers to the geometricaldisplacement or height of the thin film deposited pole piece at thelocation where the same is deposited over a coil. The result is that theouter surface of the top pole piece is contoured resulting in a "step"being formed on that part of the top pole piece rearward of thetransducing gap.

The leveler layer has a forward leveler section located adjacent thefront gap section of the top pole piece layer, and a rearward levelersection located at predetermined distance from and rearward of the frontgap section of the top pole piece layer. A superstrate having arelatively planar support surface is placed on the forward levelersection and rearward leveler section and leaves a space between therelatively planar support surface of a substrate and the contoured outersurface of the top pole piece layer. This space is remote from andrearward of the tape engaging surface.

The known prior art magnetic tape heads have the disadvantage of havingsignificant portions of the tape engaging surface fabricated frommaterials that are not highly resistive to being abraded by a magneticmedia being transported thereacross. In the Prior Art magnetic headillustrated in FIG. 1, the protective overcoat layer and the adhesivefiller, and to a lesser extent the insulating material in the gap, isexposed to and abraded by a moving magnetic media. Further, thematerials used for the substrate, the superstrate, and for adhering thesuperstrate to the top magnetic pole piece have different abradingcharacteristics resulting in a number of different materials definingthe tape engaging surface.

FIG. 2 of the EPO Publication No. 0 051 123 and U.S. Pat. Nos. 4,490,760and 4,396,967 disclose magnetic head structures wherein the protectivelayer or overcoat layer, fabricated from soft material, form part of thetape engaging surface. The amount of soft material present on the tapeengaging surface affects the magnetic tape head life due to the softmaterials eroding at a higher rate than the other materials likewiseforming part of the tape engaging surface. The dissimilar materialsdefining the tape engaging surface are eroded at different rates whenabraded by a magnetic media being transported thereacross, and if thesofter materials abrade at a significantly higher rate, the life andperformance characteristics of the magnetic head are directly affected.

Typically soft materials used in the assembly of the magnetic head, i.e.epoxies or adhesives, will easily smear and erode causing a conditionknown as a "wash-out" of the eroded material. This condition occurs as aresult of the edges of the soft material, which are located adjacent aharder material, i.e. an epoxy adhesive adjacent a ferrite pole piece,wearing in an uneven manner. This uneven abrading typically results in a"groove" being formed at the boundary of the dissimilar materials. Theso formed "groove" then becomes filled with debris which is carried tothe "groove" by the moving magnetic media. As the "groove" becomesfilled with material, a raised rib forms thereacross which causes thetape to be lifted off the tape engaging surface forming a wear point.The result is that the tape is urged away from the transducing gapreducing the efficiency of the magnetic media-to-head contact. Also, thedebris accumulated in the so formed "groove" may flake off, may becomeimbeded in the magnetic media, or may scratch the surface of themagnetic media, all of which are highly undesirable.

In magnetic tape head applications using a magnetic head structuredescribed above, the magnetic tape head life is determined by: (1) thewear characteristics of the softest material of the assembly which formspart of tape engaging surface exposed to being abraded by the magnetictape, or (2) the ability of the softest material to be resistive tobeing abraded by a moving magnetic tape.

The present invention overcomes several of the disadvantages associatedwith the prior art magnetic heads. One advantage of the presentinvention is that the materials used for fabricating the substrate andsuperstrate are formed of a material, such as for example ceramicAluminum Oxide-Titanium Carbide or ceramic Silicon Carbide, which ishighly resistive to being abraded by a magnetic tape being transportedthereacross.

Another advantage of the present invention is that a leveler layer canbe placed on top of the top pole piece and a superstrate can be placedonto the leveler layer. This results in a small, thin glue line, oradhesive line, being present between the leveler layer and superstrateat the tape engaging surface. As a result, the abrading effect on thethin glue line, or adhesive line, is minimized, thereby increasing themagnetic tape head life because substantially all of the tape engagingsurface is more resistive to being abraded by a moving magnetic tape.

Another advantage of the present invention is that the formation of theunwanted grooves in the tape engaging surface, associated with the priorart, is avoided thereby eliminating the problem of the magnetic tapelifting off from the tape engaging surface. As a result, improvedmagnetic tape head-to-tape contact and better head-tape performancecharacteristics are obtained.

Another advantage of the present invention is that magnetic tape headsusing thin film magnetic head assemblies having smaller transducing gapsand extremely small adhesive lines can be fabricated, using theteachings of the present invention enabling such magnetic tape heads totake advantage of the characteristics of thin film transducers. Suchmagnetic head assemblies can be used in multitrack, high density, taperecording applications. Such magnetic head assemblies will have improvedoperating characteristics and enhanced magnetic tape head life.

Another advantage of the present invention is that by use of a coilwindings receiving trench, located within an integral bottom pole piecelateral wall structure, the internal physical separation distancebetween the top and bottom pole pieces can be increased. A magnetic tapehead fabricated with the coil windings receiving trench results inimproved efficiency and operating characteristics.

Another advantage of the present invention is that the thin filmmagnetic head assembly formed by using the teachings of the presentinvention can be used to fabricate a multitrack, magnetic tape head foruse in high tape speed, high density recording applications. One exampleof such an application is an 18 track magnetic tape head that can beused in a high density, tape storage system such as the IBM Model 3480tape storage system.

Another advantage of the present invention is that coil windings, whichare located in the coil windings receiving trench formed in the laterallayer, can be a spiral wound coil, a helical wound coil, or a single ormultiplanar or multiple layer coil or the like.

Another advantage of the present invention is that the apparent overallthickness of the top and bottom pole pieces used to define the tapeengaging surface can be made symmetrical or the geometrical dimensionsthereof, such as the thickness of the pole piece layer, can becontrolled. This is accomplished by controlling the thickness of thebottom pole piece and lateral wall layer during the deposition orplating process, and then controlling the thickness of the leveler layerdeposited or plated onto the top pole piece.

Another advantage of the present invention is that the overall thicknessof the bottom pole piece, including the depth of the coil windingsreceiving trench formed therein, can be precisely controlled bycontrolling the thickness of the lateral layer during the deposition ofthe same onto the bottom pole piece. In the alternative, the thicknessof the bottom pole piece can be controlled during the deposition orplating process to form a thick layer film of magnetic material, andthen controllably removing, by means of a mask and an ion beam, aselected center section of the material of the thick film pole piece toform a central trench therein which functions as the coil windingsreceiving trench.

Another advantage of the present invention is that the pole pieces usedin practicing this invention can have dimensions, that is pole facethicknesses, in the order of about 5 microns to about 25 microns,depending on the desired operating characteristics of the magnetic tapehead. In the preferred embodiment, the desired range would be in therange of about 8 microns to about 15 microns.

Another advantage of the present invention is that the substrate andsuperstrate can be fabricated from a relatively hard material such asceramic Silicon Carbide [SiC] or ceramic Aluminum Oxide-Titanium Carbide[Al₂ O₃ -TiC]. The pole pieces, lateral layer and leveler layer used inpracticing this invention can be fabricated from nickel-iron; and theboundary between the lateral layer and bottom pole piece would benon-existent. The thin gap defining material can be Al₂ O₃, and have adimension in the order of about 1 micron or less. The glue line oradhesive line between the leveler layer and superstrate can be in theorder of 5 microns or less and in the preferred embodiment is in theorder of 1 micron.

Another advantage of the present invention is that a thin film magnetictape head can be fabricated having a lateral wall layer defining a coilwindings receiving trench alone. Alternatively, a thin film magnetichead can be fabricated having a lateral wall layer defining a coilwindings receiving trench and a leveler layer, located on the top polepiece, to support a planar superstrate.

DESCRIPTION OF THE DRAWINGS

These and other advantages of the invention will be readily apparentwhen considered in light of the detailed description hereinafter of thepreferred embodiment and when considered in light of the drawing setforth herein which includes the following Figures:

FIG. 1 is a diagrammatic illustration of a Prior Art thin film magnetichead having a pair of deposited pole pieces which enclose a depositedcoil having a plurality of coil windings;

FIG. 2 is a diagrammatic illustration of a Prior Art magnetic headhaving a bottom pole piece formed from a ferrite material, wherein thebottom pole piece has a glass filled slot to receive and support a coilhaving a plurality of coil windings, and a deposited top pole pieceencloses the coil windings;

FIG. 3 is a pictorial representation, in cross-section, of a thin filmmagnetic tape head having a coil windings receiving trench defined by alateral wall layer and having a leveler layer deposited onto the toppole piece and a rearward support section for supporting a superstrate;

FIG. 4 is a top plan view of a thin film magnetic tape head illustratedin FIG. 3;

FIG. 5 is a partial pictorial representation, in cross-section, of oneembodiment of a thin film magnetic transducer having a substrate forsupporting a bottom pole piece layer with a coil windings receivingtrench formed therein, a deposited top pole piece, a leveler layerdeposited onto the top pole piece and a superstrate;

FIG. 6 is a partial pictorial representation, in cross-section, ofanother embodiment of a thin film magnetic head having a substrate forsupporting a bottom pole piece layer with a coil windings receivingtrench formed therein, a deposited top pole piece and a superstrate;

FIG. 7 is a partial pictorial representation, in cross-section, of yetanother embodiment of a thin film magnetic head having a substrate forsupporting a bottom pole piece layer, coil windings deposited onto thebottom pole piece, a deposited top pole piece, a leveler layer depositedonto the top pole piece and a superstrate;

FIG. 8 is a partial pictorial representation, in cross-section, of thetape engaging surface including the magnetic transducing gap of theembodiment of the thin film magnetic head illustrated in FIG. 5 hereof;

FIG. 9 is a partial pictorial representation, in cross-section, of thetape engaging surface including the magnetic transducing gap of theembodiment of the thin film magnetic head illustrated in FIG. 6 hereof;

FIG. 10 is a partial pictorial representation, in cross-section, of thetape engaging surface including the magnetic transducing gap of theembodiment of the thin film magnetic head illustrated in FIG. 7 hereof;

FIGS. 11 A and 11 B are pictorial representations of (i) a deposited,thick film bottom pole piece having an ion milling mask placed thereon,and (ii) a lateral wall layer defining a coil windings receiving trenchformed by ion beam removal of a controlled portion of the bottom polepiece material to form the same, respectively;

FIGS. 12 A and 12 B are pictorial representations of (i) a partiallydeposited, thin film bottom pole piece having a mask placed thereon toprevent further material from being deposited on a selected area of thepartially deposited pole piece, and (ii) a lateral wall layer defining acoil windings receiving trench formed by having a selected area of thebottom pole piece masked to prevent deposition of material in theselected area during continued deposition of the bottom pole piecematerial to form the same, respectively; and

FIGS. 13, 14 and 15 are a series of block diagrams depicting the varioussteps of method for forming the thin film magnetic tape head illustratedin FIG. 3 hereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As described hereinbefore, the thin film magnetic head shown in FIGS. 1and 2 are Prior Art magnetic heads having deposited top pole pieces.During the deposition process, the top pole piece has a contoured outersurface having a step such that the physical shape taken by thedeposited layer varies from the forward gap section, which functions asthe other side of a magnetic transducing gap, to the center of thelayer. The center of the layer, which encloses the coil windings,defines the "step" and the height thereof. The rear portion of the toppole piece is referred to as the rear magnetic closure portion of thetop pole piece and forms part of a rear magnetic closure section. As isapparent from the illustration of FIGS. 1 and 2, the protective overcoatmust conform to the step of the contoured outer surface of the topmagnetic pole piece.

In the Prior Art magnetic heads, the thick filler material locatedbetween the protective overcoat and the superstrate, as well as theprotective overcoat itself, are engaged by and abraded by the movingmagnetic media. The large area of the adhesive or filler and thethickness of the protective overcoat result in a disadvantage of thePrior Art magnetic heads overcome by the teachings of this invention.

The protective overcoat material, typically formed of such materialssuch as sputtered SiO₂ or Al₂ O₃, is softer than the materials used tofabricate the other elements of the magnetic head, with the exception ofplated NiFe. An adhesive or filler layer is used to fill the gap betweenthe tope pole piece and the superstrate. The adhesive or filler layer 58in FIG. 1 and 81 in FIG. 2 form part of the tape engaging surface of themagnetic head. As a result, the softer materials used for the protectiveovercoat and adhesive or filler layer are subject to eroding whenengaged by a moving magnetic media.

In certain other implementations, a superstrate with a planar supportsurface, and a bonding material, such as glass, adhesive or epoxy areused between the superstrate and the top pole piece to bond or join thesame together. As a result, the bonding material forms a thick or wideline or width of yet another dissimilar material that is placed into thetape engaging surface. Such material is abraded by the magnetic tapebeing transported thereacross resulting in the disadvantages describedin detail hereinabove.

Thin film magnetic heads generally, and thin film magnetic tape headsspecifically, are used in applications having high density recording andreproducing rates, say in the order of 19,000 Bits Per Inch (BPI), andin the order of 25,000 Flux Reversals Per Inch (FRPI). In certain thinfilm magnetic tape head applications, the magnetic tape may be movedacross the tape head at speeds in the order of 80 inches per second ormore. Thus, the problem of abrading of the thin film magnetic tape headby the magnetic tape directly affects the operating characteristics andlife of the thin film magnetic tape head. In order to solve theseproblems, the fabrication of the thin film magnetic heads is now beingdirected to structures formed of materials which are highly resistive tobeing abraded by a magnetic tape being transported thereacross.

Thin film magnetic heads have relatively thin magnetic gaps, say in theorder of one micron or less, and the material used in a gap is abradedby the magnetic tape moving thereacross. However, the cross-sectionalarea of a thin film gap is very small compared to the overallcross-section area of the tape engaging surface. As a result, the wearlife of a thin film magnetic head is greatly improved when the structureof the magnetic head is formed of elements which have improvedcharacteristics so as to be resistive to being abraded.

The embodiment of the thin film magnetic head illustrated in FIG. 3 isshown without a superstrate being affixed to the thin film headassembly. The magnetic head structure is formed to provide a tapeengaging surface that is highly resistive to being abraded by a magnetictape. In the structure of FIG. 3, the thin film magnetic tape head,shown generally as 100, has a substrate 102 formed of a material whichis highly resistive to being abraded by a magnetic media being movedthereacross. Typical materials that may used for the substrate areceramic Al₂ O₃ -TiC, ceramic SiC or other similar materials that arehighly resistive to being abraded.

A magnetic bottom pole piece layer 104, which in the preferredembodiment is a chemically plated pole piece, is located on thesubstrate 102. In the embodiment illustrated in FIG. 3, the thickness ofthe deposited pole piece is in the order of about 5 microns to about 25microns, depending on the application. The preferred range is in theorder of about 8 microns to about 15 microns. The pole piece materialmay be a Nickel-Iron alloy material having in the order of 81% nickeland 19% iron. The bottom pole piece layer 104 has a lateral wall layer117 having a continuously deposited (i.e. no apparent boundary existsbetween the bottom pole piece 104 and the lateral wall layer 117)forward wall section 110 and a continuously deposited rearward wallsection 112 with the forward wall section 110 positioned at apredetermined location on the substrate 102. The dashed lines 114 and115 illustrate the portions thereof which form the wall sections 110 and112, but no discrete boundary layer exists between the wall sections 110and 112 and the bottom pole piece 104. The rearward wall section 112 islocated rearward of and extends in a spaced opposed relationship fromthe forward wall section 110.

The lateral wall layer 117, formed of a magnetic material, is formed onor as part of the bottom pole piece layer 104. The lateral wall layer117 is formed of predetermined thickness and is positioned on and formsan integral part of the bottom pole piece layer 104. Two methods forforming lateral wall layer 117 and the coil windings receiving trenchare discussed in connection with FIGS. 11 A, 11 B, 12 A and 12 B.

The forward wall section 110 and a rearward wall section 112 defining acoil windings receiving trench 116 therebetween.

The forward wall section 112 of the lateral wall layer 117 is located onthe bottom pole piece 104 with the forward wall section 112 establishingone side of a transducing gap 118. The rearward wall section 112 ispositioned a predetermined distance rearward from the front wall section110 and contiguous the rearward wall section 112 forming one side of arear magnetic closure section 128. This results in the coil windingsreceiving trench 116 being positioned on the bottom pole piece 104 nearthe front wall section 110. The bottom pole piece 104 forms a bottomenclosure for the coil windings receiving trench 116.

The following description relates to the structure of the various layersthat are deposited into the combined pole piece 104--lateral wall layer117 described hereinbefore, to form the thickness of the transducer gap118 and to define an insulating structure for enclosing the coilwindings, both within the coil windings receiving trench 116 and on therearwardly extending portion 129 of the bottom pole piece 104. The coilmay comprise a single layer coil having a plurality of coil windings ormay comprise a multiplanar coil having a plurality of coil windings.

An insulating layer of Al₂ O₃, shown as layer 126, is sputtered on theentire subassembly. That portion of the sputtered layer located on topeof the rearward wall section 112 is removed and the sputtered insulationlayer 126 remains on top of the forward wall section 110, on thatportion of the bottom pole piece 104 defining the bottom of the coilwinding receiving trench 116 and on the rearwardly extending portion 129of the bottom pole piece 104.

A first layer of photoresist 130 is then deposited onto the insulatinglayer 126 to support the first layer of coil windings 132 of thatportion of the multiplanar coil winding located in the coil windingsreceiving trench 116, which coil windings 132 likewise extend to therearwardly extending portion 129 of the bottom pole piece 128.

A portion of the first photoresist layer 130 is located in the coilwindings receiving trench 116 and a portion thereof is located rearwardof the rearward wall section 112. The first layer coil winding 132 issupported by the first photoresist layer 130, both within the coilwindings receiving trench 116 and over the rearwardly extending section129 of the bottom pole piece.

A second photoresist layer 136 is deposited onto the first layer of thecoil windings 132 and the first photoresist layer 130 to enclose thefirst layer of coil windings 132.

A second layer of coil windings 140 is formed on the second photoresistlayer 136, both within the coil windings receiving trench 116 and overthe rearwardly extending portion of the bottom pole piece 129.

Thereafter a third photoresist layer 146 is deposited onto the secondlayer of coil winding 140, both within the coil windings receivingtrench 116 and over the rearwardly extending portion 129 of the bottompole piece 128.

The above is referred to hereinafter as the "insulating structure",which in FIG. 3 is shown generally as 155, and, that the portion of theinsulating structure defining the thickness of the magnetic transducinggap is referred to herein as the "thin gap defining portion", which inFIG. 3 is shown generally as 126, of the "insulating structure" 155. Theportion of the "insulating structure" enclosing the multiplanar coilwindings between the top and bottom pole pieces is referred to herein asthe "thick coil windings enclosing portion," which in FIG. 3 is showngenerally as 157, of the insulating structure 155.

A deposited magnetic top pole piece layer 150 has a front gap section152 and a rear magnetic closure portion 154. The front gap section 152of the top pole piece 150 is positioned on the thin gap defining portion126 of the insulating structure and adjacent the front wall section 120of the lateral wall layer 117 which is contiguous with the front gapportion 114 of the bottom pole piece layer 104 establishing thetransducing gap 118. The rear magnetic closure portion 154 of the toppole piece 150 is contiguous the rearward wall section 112 at a locationrearward of and spaced from the transducing gap 118, to form the otherside of the rear magnetic closure section 128. The bottom surface of thetop pole piece layer 150 bridges the forward wall section 116 and therearward wall section 112 of the lateral wall layer forming a topenclosure for the coil windings receiving trench 116.

As illustrated in FIG. 3, during the deposition of the top pole piece, asupport section 156 of the top pole piece layer 150 is deposited on topof the third photoresist layer 144 described above, the coil windings132 which extend rearward to the location where the multiplanar coilwindings 132 and 146 are electrically connected to an electricalconducting connecting means, which electrical conducting connectingmeans is shown as 180 as shown in FIG. 4.

A leveler layer, shown generally as 158, having a forward levelersection 160 and a rearward leveler section 162 is deposited specificallyon the front gap section 152 of the top pole piece 150 and on therearwardly located support section 156. The leveler layer 158 has athickness which is slightly greater than the height of the step of thetop pole piece 150. The forward leveler section 160 is deposited ontothe front gap section 152 of the top pole piece 150 while the rearwardleveler section 162 is continuously deposited onto the support section156 of the top pole piece 150. Dashed lines 164 and 166 illustrate thecommencement of the deposited leveler layer 158. The rearward levelersection 162 is located a predetermined distance from and rearward of therear wall section 122 and rearward of the magnetic transducing gap 148and rear magnetic closure section 128. The forward leveler section 160and rearward leveler section 162 are adapted to receive and support asuperstrate.

A superstrate, omitted from FIG. 3 for clarity, is affixed to theleveler layer 158. However (in a similar manner to superstrate 248 inFIG. 5), the structure of FIG. 3 would have a planar superstrate affixedto the leveler layer 158 by specifically attaching the same to theforward leveler section 160 and the rearward leveler section 162.Typically, the superstrate is preferably formed of the same materials asthe substrate. The adhesive line, formed at the boundary of the levelerlayer forward wall section 160 and the undersurface of a superstrate, isvery thin, say in the order of 5 microns or less. As such, thecross-section area of the adhesive line presented to the tape engagingsurface is extremely small, and will not adversely affect the abradingcharacteristics of the total tape engaging surface.

In FIG. 3 the tape engaging surface, when the final magnetic headassembly is ground and polished, is formed of the substrate 102, theforward gap section 108 of the bottom pole piece 104, the forward wallsection 112 of the lateral layer 117, the thin gap defining portion 126of the insulating structure 155 located in transducing gap 118, thefront gap section 152 of the top pole piece 150, the forward wallsection 160 of the leveler layer 158 and the thin adhesive line andsuperstrate (not shown in FIG. 3, but equivalent to the superstrateillustrated as element 248 in FIGS. 5 and 8).

FIG. 4 illustrates, in the top view thereof and without a superstrate,the relationship between the substrate 102, the bottom pole piece 104,the forward leveler section 160 and the rearward leveler section 162 andthe coil windings 132 and 146 (shown as dashed lines). The coil windings136 and 146 and the insulating structure enclosing the same have aportion thereof located in the coil windings receiving trench 116 and aportion thereof located over the rearwardly extending portion 129 of thebottom pole piece 104, respectively. The forward leveler section 160 andrearward leveler section 162 of the leveler layer 158 are shown as beingdeposited onto front gap section 152 of the top pole piece 150 (FIG. 3)and the support section 156 (FIG. 3), respectively. The support section156 of the top pole piece 158 (FIG. 3) is deposited on the thirdphotoresist layer 144 as noted above. The forward leveler section 160and the rearward leveler section 162 are positioned to receive andsupport a superstrate.

Electrical connecting means 180 are attached to the coil windings 132and 146 to pass electrical signals between the thin film magnetic headand an output circuit.

FIGS. 5, 6 and 7 disclose three embodiments of thin film magnetic headsthat are fabricated using the teachings of this invention. As willbecome apparent from the following discussions, a thin film magnetichead can use be fabricated with: (i) the coil windings receiving trenchand the leveler layer, as is depicted by FIG. 5; (ii) the coil windingsreceiving trench alone, as is depicted by FIG. 6; or (iii) the levelerlayer alone, as is depicted by FIG. 7.

Specifically, FIG. 5 discloses that the substrate 200 has a bottom polepiece layer 202 that has the lateral wall section in lieu of a separatelayer formed to be integral therewith which is an alternativeconstruction. The lateral wall section is shown as 204. The lateral wallsection 204 has a forward wall section 206 and a rearward wall section208. The forward wall section 206 and the rearward wall section 208define a coil windings receiving trench 210. The coil windings receivingtrench 210, in this embodiment, encloses stacked coil windings 212 whichform a part of the multiplanar coil of the magnetic head discussed inconnection with FIG. 5. The coil windings 212 are encapsulated in athick coil windings enclosing portion 216 of an insulating structure214. The insulating structure 214 also has a thin gap defining portion220. The thin gap defining portion 220 is deposited onto the forwardwall section 206 of the lateral wall section 204.

A top pole piece layer 230 has a front gap section 232 that is locatedadjacent to the front gap section 234 formed on the forward wall section206 which functions as the gap for the bottom pole piece 202. Also, thesupport section 246 is formed with the top pole piece 250. The front gapsection 234, which is part of the bottom pole piece 202, forms one sideof a magnetic transducing gap 237 and the front gap section 232 of toppole piece 230 forms the other side of the transducing magnetic gap 237.The thickness of the magnetic gap 237 is established by the thickness ofthe thin gap defining portion 220 of the insulating structure 214.

The top pole piece 230 bridges the forward wall section 206 of thelateral wall layer 204, which likewise is the forward wall sectiondefining the coil winding receiving trench 210 having the thin gapdefining portion 220 thereon, to the rearward wall section 208 of thelateral wall section 204 which defines the other side of the coilwinding receiving trench 210. At the transducing gap 237 located on thetape engaging surface, the front gap section 232 of the top pole piecelayer 230 is separated from, but is supported on, the front gap section234 through the thin gap defining portion 220 of insulating structure214, which establish the thickness of the transducing gap 237. However,the rear magnetic closure portion 236 of the top pole piece 230physically contacts the rearward wall section 208 of the lateral wall204, which is part of the bottom pole piece 202, to form a rear magneticclosure section 238 to complete the reluctance path for the magneticflux. Thus, the rearward wall section 208 of the lateral wall layer 204and the rearwardly extending portion 218 of the bottom pole piece 202structurally support the rear magnetic closure portion 236 of the toppole piece 230 while concurrently serving as the rear magnetic closuresection 238 for the thin film magnetic head as described above.

A leveler layer 240 having a forward leveler section 242 and a rearwardleveler section 244, located rearward of lateral wall section 208,defines a leveling layer to enable a relatively planar superstrate 248to be affixed to the assembly. The superstrate 248 does not have to befabricated or processed in a manner to conform the same to the step ofthe contoured outer surface of the top pole piece 230. The rearwardleveler section 244 is supported by the separate support section 246,formed as part of the top pole piece layer 236, in a manner similar tothat in which the support section 162 of FIG. 3 is formed.

As a result of the above structure, a space 250, located remotely fromand rearward of the transducing gap 237, is formed between the bottom ofthe superstrate 248 and the step of the contoured outer surface of thetop pole piece 230. Typically the space 250 is filled with an insulatingglue or adhesive shown as 252. The superstrate is attached to theforward leveler section 242 and the rearward leveler section 244 bymeans of an adhesive, such as a low temperature epoxy that has a curingtemperature below the temperature which would cause a change in themagnetic characteristics of the pole pieces 202 and 230. The substrate248 is attached to and extends between the forward leveler section 240and the rearward leveler section 244 enclosing the step of the contouredouter surface of the top pole piece 230, it being noted that the step isremote from the tape engaging surface.

The resulting glue line, or adhesive line, located at the boundarydepicted by arrow 254, has a thickness of about 5 microns or less, whichis substantially less than the thickness of the adhesive and fillerlines shown in FIGS. 1 and 2 of the Prior Art magnetic heads.

In the embodiment of FIG. 6, a substrate 300 has a deposited bottom polepiece 302 that has the lateral wall layer formed to be integraltherewith, which is shown as lateral wall section 304. The lateral wallsection 304 defines in the interior thereof a coil windings receivingtrench 308. The coil windings receiving trench 308 encloses, in thisembodiment, a stacked coil windings 312 which form a part of themultiplanar coil of a magnetic head similar to that discussed inconnection with FIG. 3. The coil windings 312 are encapsulated in thickcoil windings enclosing portion 316 of the insulating structure showngenerally as 346. The thick coil windings enclosing portion 316 is partof the insulating structure 346 which includes a thin gap definingportion 320. The thin gap defining portion 320 is deposited onto theforward wall section 322 of the lateral wall section 304. The forwardwall section 322 functions as one side of the transducing gap 326.

A top pole piece 330 has a front gap section 332 that is locatedadjacent to and spaced from the front wall section 322 of the lateralwall section 304. The width of the spacing is determined by the thin gapdefining portion 320 of the insulating structure 346. The front gapsection 332 of the top pole piece 330 forms the other side of themagnetic transducing gap 326. The thickness of the magnetic transducinggap 326 is controlled by controlling the thickness of the thin gapdefining portion 320 of the insulating structure 346.

The top pole piece 330 bridges from the forward wall section 322, whichlikewise is the front section of the coil windings receiving trench 308,to the rearward wall section 338 of the lateral wall section 304. At themagnetic transducing gap 326 located on the tape engaging surface, thefront gap section 332 of the top pole piece layer 330 is separated from,but is supported on, the front wall section 322 of the lateral wallsection 304 through the thin gap defining portion 320 of the insulatingstructure 346.

The rear magnetic closure portion 336 of the top pole piece 330physically contacts the rearward wall section 338 of the lateral wallsection 304, which is integral with the bottom pole piece 302, to form arear magnetic closure section 340 to complete the reluctance path forthe magnetic flux. The rearward wall section 338 of the lateral wallsection 304, supported by the bottom pole piece 302, structurallysupports the rear magnetic closure portion 336 of the top pole piece 330while concurrently serving as the rear magnetic closure section 340 forthe thin film magnetic head. A protective layer 347 is provided.

The resulting adhesive line or glue line, shown as 348, is slightlythicker in dimension than that discussed in FIG. 5, and could be in theorder of 5 microns or more, which is still less than the thickness ofthe adhesive lines shown in FIG. 1 and FIG. 2 of the prior art.

The embodiment of a thin film magnetic head assembly illustrated in FIG.7 incorporates a thin film magnetic head transducer which is similar inconstruction to that illustrated as FIG. 1 and labeled as Prior Art,except that the magnetic head in FIG. 7 has a multiplanar coil windingsas compared to a single coil winding. However, the thin film magnetichead assembly has a leveler layer as will be described hereinbelow.

FIG. 7 discloses that the substrate 400 has a bottom pole piece 402having a predetermined thickness that has been deposited thereon. Thebottom pole piece 402 has a front gap section 404 that defines one sideof a magnetic transducing gap 406.

The stacked or multiplanar coil windings 408, which form a part of themultiplanar coil of a magnetic head, are encapsulated in thick coilwindings enclosing portion 416 of an insulating structure showngenerally as 456. The thick coil windings enclosing portion 416 is partof an insulating structure 456 which includes a thin gap definingportion 420. The thin gap defining portion 420 is deposited onto thefront gap section 404 of the bottom pole piece 402 to define thetransducing gap 406.

A deposited top pole piece 430 has a front gap section 432 which islocated adjacent to the front gap section 404 of the bottom pole piece402. The front gap section 404 of the bottom pole piece forms one sideof a magnetic transducing gap 438 and the front gap section 432 of thetop pole piece 430 forms the other side of the magnetic transducing gap406. The thickness of the magnetic transducing gap 406 is established bythe thickness of the thin gap defining portion 420 of the insulatingstructure 456.

The top pole piece 430 includes a rear magnetic closure portion 436which physically contacts or is contiguous the rearwardly extendingportion 440 of the bottom pole piece 402 to form a rear closed magneticsection 440 to complete the reluctance path for the magnetic flux.

A leveler layer 442 having a forward leveler section 444 and a rearwardleveler section 446 defines a leveling means to enable a superstrate448, having a relatively planar support surface, to be affixed to theassembly without having to conform the same to the stepped contouredouter surface of the top pole piece 430. A space 450, remote from thetransducing gap 406, is formed between the bottom of the superstrate andthe stepped contoured outer surface of the top pole piece 430. Typicallythe space 450 is filled with an insulating glue or adhesive shown as452. The superstrate 448 is affexed to the leveler layer by means of anadhesive, having the characteristics reference above, and the resultingthe glue line or adhesive line, located at the boundary depicted as 454,would have a thickness of about 5 microns or less, which issubstantially less than the thickness of the adhesive line shown inFIGS. 1 and 2 of the Prior Art magnetic heads. This is about the samethickness as discussed above with respect to FIG. 5.

In FIG. 8, the illustration depicts a view looking into the magnetic gapof a multitrack magnetic tape head formed from a plurality of thin filmmagnetic tape head assemblies shown in FIG. 5. The magnetic tape isshown to be transported in either direction shown by arrow 460. Amagnetic head assembly, shown generally as 464, is separated from anadjacent, spaced aligned magnetic head assembly 466, of identicalstructure, by an insulating material 470.

The tape engaging surface for magnetic head 464 is defined by thesubstrate 200, the bottom pole piece 202, the front wall section 206 ofthe lateral wall section 204, the thin gap defining portion 220 of theinsulating structure 214, the front gap section 232 of the top polepiece 230, the front leveler section 242 of the leveler layer 240, theglue line 234 and the superstrate 248.

In FIG. 9, the illustration depicts a view looking into the magnetic gapof a multitrack magnetic tape head formed from a plurality of thin filmmagnetic tape head assemblies shown in FIG. 6. The magnetic tape isshown to be transported in either direction shown by arrow 480. Amagnetic head assembly, shown generally as 484, is separated from anadjacent, spaced aligned magnetic head assembly 486, of identicalstructure, by an insulating material 346.

The tape engaging surface for magnetic head 484 is defined by thesubstrate 300, the bottom pole piece 302, the lateral wall layer 304,the thin gap defining portion 320 of the insulating structure 346, thefront gap section 332 of the top pole piece 330, the front edge of thebonding material layer 346, and the superstrate 342.

In FIG. 10, the illustration depicts a view looking into the magneticgap of a multitrack magnetic tape head formed from a plurality of thinfilm magnetic tape head assemblies shown in FIG. 7. The magnetic tape isshown to be transported in either direction shown by arrow 500. Amagnetic head assembly, shown generally as 504, is separated from anadjacent, spaced aligned magnetic head assembly 506, of identicalstructure, by an insulating material 510.

The tape engaging surface for magnetic head 504 is defined by thesubstrate 400, the front gap section 404 of the bottom pole piece 402,the thin gap defining portion 420 of the insulating structure 456, thefront gap section 432 of the top pole piece 430, the front levelersection 444 of the leveler layer 442, the glue line 454 and thesuperstrate 448.

FIG. 11 A is pictorial representations of a deposited, thick film bottompole piece 520 supported on a substrate 522 and having an ion beam mask524 placed around the outer edges thereof leaving the central area 528of the bottom pole piece layer 520 exposed. The unmasked or exposedcentral surface 528 is then milled using a ion beam, depicted by dashedlines 526, to controllably remove material from the central area 528 ofthe bottom pole piece 520 to form a lateral wall layer defining a coilwindings receiving trench.

FIG. 11 B illustrates the final integral bottom pole piece layer-lateralwall layer assembly. In FIG. 11 B, the fabricated bottom pole piece 520is supported by a substrate 522 and has a lateral wall layer section 530integral therewith. The lateral wall section 530 defines a coil windingsreceiving trench 532 having the bottom enclosure defined by the bottompole piece 520.

FIG. 12 A is pictorial representations of a deposited, thin film bottompole piece 570 supported on a substrate 572 and having a plating maskplaced 574, of an appropriate thickness, placed thereon at the centralarea of the bottom pole piece 570 leaving the portions 576 exposed. Theunmasked areas or exposed portions 576 are then subjected to a platingsolution to controllably continuously add plating material to theportions 576 of the bottom pole piece 570 to form a lateral wall layerdefining a coil windings receiving trench.

FIG. 12 B illustrates the final integral bottom pole piece layer-lateralwall layer assembly. In FIG. 12 B, the integral plated bottom pole piecelayer 570 supports a lateral wall section 584 having wall sections 586.The lateral wall sections 586 define a coil windings receiving trench588 therebetween. Dashed lines 590 are shown in FIG. 12B to depict thecommencement of the portion of the continuously plated or depositedlateral wall section 586 from the plated bottom pole piece layer 570.

FIGS. 13, 14 and 15 depict, by means of a block diagram, the steps of amethod for producing the magnetic tape head of FIG. 3. However, it isreadily apparent to a person skilled in the art that certain of thesteps could be omitted and/or replaced to produce other embodiments ofthin film magnetic tape heads, such as for example, the thin filmmagnetic heads illustrated in FIGS. 5, 6 and 7, using the teaching ofthis invention.

In FIG. 13, the steps shown therein are:

(I) clean substrate as illustrated by box 600; This may be performed bya high pressure scrub detergent with an ionized wash under pressure toremove cleaning material or any organic matter;

(II) ion mill substrate to remove any inorganic matter as illustrated bybox 602; This may be performed by use of a standard ion milling machine;

(III) deposit plating base on substrate as illustrated by box 604; Thismay be performed by sputtering a thin metallic layer;

(IV) photoresist, expose and develop bottom pole piece pattern asillustrated by box 606; This may be performed by using commerciallyavailable photoresist material;

(V) electroplate bottom pole piece with NiFe as illustrated by box 608;This may be performed by using an appropriate nickel-iron solution;

(VI) strip resist as illustrated by box 610; This may be performed byusing commercially available stripping material;

(VII) photoresist, expose and develop trench pattern as illustrated bybox 612; This may be performed by using commercially availablephotoresist material;

(VIII) electroplate bottom trench with NiFe as illustrated by box 614;This may be performed by using an appropriate nickel-iron solution;

(IX) strip resist as illustrated by box 616: This may be performed byusing commercially available stripping material;

(X) sputter Aluminum Oxide to form gap as illustrated by box 618; Thismay be performed by using commercially available sputtering apparatusand a selected thickness thereof depending on the application;

(XI) photoresist, expose and develop rear magnetic closure section andopening as illustrated by box 620; This may be performed by usingcommercially available photoresist material;

(XII) etch Aluminum Oxide from rear magnetic closure section asillustrated by box 622; This may be performed by using commerciallyavailable chemical etching solutions;

(XIII) ion mill to remove plating base from subassembly as illustratedby box 624; This may be performed by use of a standard ion millingmachine;

(XIV) photoresist, expose and develop first planarization pattern asillustrated by box 626; This may be performed by using commerciallyavailable photoresist material;

(XV) hard bake photoresist at preselected temperature with a magneticfield as illustrated by box 628; This may be performed by hard bakingresist in a vacuum in an appropriate magnetic field;

The discussion now goes from FIG. 13 from line X--X to line X--X of FIG.14:

(XVI) deposit plating base as illustrated by box 630; This may beperformed by depositing an appropriate thin metallic layer;

(XVII) photoresist, expose and develop first coil pattern as illustratedby box 632; This may be performed by using commercially availablephotoresist material;

(XVIII) deposit copper for first coil as illustrated by box 634; Thismay be performed by electroplating copper to form first coil to aselected thickness;

(XIX) strip resist as illustrated by box 636; This may be performed byusing commercially available stripping material;

(XX) ion mill plating base as illustrated by box 638; This may beperformed by use of a standard ion milling machine;

(XXI) photoresist, expose and develop second planarization layer asillustrated by box 640: This may be performed by using commerciallyavailable photoresist material; (XXII) hard bake photoresist atpreselected temperature with a magnetic field as illustrated by box 642;This may be performed by hard baking resist in a vacuum in anappropriate magnetic field;

(XXIII) deposit plating base as illustrated by box 644; This may beperformed by depositing an appropriate thin metallic layer;

(XXIV) photoresist, expose and develop first coil pattern as illustratedby box 646; This may be performed by using commercially availablephotoresist material;

(XXV) deposit copper for second coil as illustrated by box 648; This maybe performed by electroplating copper to form second coil to a selectedthickness;

(XXVI) strip resist as illustrated by box 650; This may be performed byusing commercially available stripping material;

(XXVII) ion mill plating base as illustrated by box 652; This may beperformed by use of a standard ion milling machine;

The discussion now goes from FIG. 14 from line Y--Y to line Y--Y of FIG.15:

(XXVIII) photoresist, expose and develop third planarization layer asillustrated by box 654; This may be performed by using commerciallyavailable photoresist material;

(XXIX) hard bake photoresist at preselected temperature with a magneticfield as illustrated by box 656; This may be performed by hard bakingresist in a vacuum in an appropriate magnetic field;

(XXX) deposit plating base on substrate as illustrated by box 658; Thismay be performed by an appropriate thin metallic layer;

(XXXI) photoresist, expose and develop top pole piece pattern asillustrated by box 660; This may be performed by using commerciallyavailable photoresist material;

(XXXII) electroplate top pole piece with NiFe as illustrated by box 662;This may be performed by using an appropriate nickel-iron solution;

(XXXIII) strip resist as illustrated by box 664; This may be performedby using commercially available stripping material;

(XXXIV) photoresist, expose and develop leveler pattern with the frontgap section and support section of a pole piece layer being unmasked toreceive leveler layer as illustrated by box 666; This may be performedby using commercially available photoresist material;

(XXXV) electroplate leveler layer with NiFe as illustrated by box 668;This may be performed by using an appropriate nickel-iron solution;

(XXXVI) strip resist as illustrated by box 670; This may be performed byusing commercially available stripping material;

(XXXVII) ion mill plating base/top pole piece/leveler plating base asillustrated by box 672; This may be performed by use of a standard ionmilling machine; and

(XXXVIII) Probe test electrical resistance of transducer as illustratedby box 674; This may be performed by use of standard electricalresistance probe test apparatus.

It is envisioned that one or more of the above steps could be used withmagnetic heads formed of different steps, but the process of forming thebottom pole layer having the lateral wall layer integral therewith asdescribed in connection with FIGS. 12 A and 12 B could likewise be usedto practice the teachings of this invention. Specifically, the processsteps for forming the lateral wall layer, or lateral wall sections, ifthe same is integral with the bottom pole piece, to define a coilwindings receiving trench and for forming the leveler layer can be usedsuccessfully with a wide range of thin film magnetic heads, such as forexample, a read-while-write head and the like.

It is also envisioned that a person skilled in the art could utilize theproduct or method disclosed herein to greatly reduce the percentage ofarea of the so called soft abrading material in any magnetic head thatis exposed to abrading on a magnetic media engaging surface such thatsubstantially all of the media engaging surface is formed of a materialthat is highly resistant to being abraded by a magnetic media.

Although the preferred embodiment disclosed herein is for magnetic tapeheads and magnetic tape head assemblies, the teachings hereof have equalapplication to other magnetic heads, such as, for example, floppy discheads, Winchester type flying heads, or the like. The teachings hereofcan be used by those skilled in the art to maximize the amount of highlyresistive material that is in the magnetic media engaging path to obtainimproved magnetic head operating characteristics and longer head life.

What is claimed is:
 1. A thin film magnetic head comprisinga substrateformed of a material which is highly resistive to being abraded by amagnetic media being moved thereacross; a bottom pole piece located onsaid substrate, said bottom pole piece having a front gap section and arearwardly extending portion with the front gap section thereofpositioned at a predetermined location on said substrate and with therearwardly extending portion thereof located rearward of and spaced fromthe front gap section; a lateral wall formed of a magnetic materialhaving a forward wall section and a rearward wall section defining acoil windings receiving trench therebetween, said lateral wall beingformed of predetermined thickness and being positioned on said bottompole piece with the forward wall section contiguous the front gapsection of said bottom pole piece establishing the forward wall sectionas one side of a transducing gap and with the rearward wall sectionbeing positioned a predetermined distance rearward from the front wallsection and contiguous the rearwardly extending portion of said bottompole piece forming one side of a rear magnetic closure section, the coilwindings receiving trench being positioned on said bottom pole piecerearward of the front gap section and forward of the rear magneticclosure section with said bottom pole piece located between the forwardwall section and the rearward wall section forming a bottom enclosurefor the coil windings receiving trench; a coil having a plurality ofcoil windings formed on said bottom pole piece and having a thicknesswhich is less than the thickness of said lateral wall, said coil havinga portion of the coil windings located in the coil windings receivingtrench and the remaining portion thereof extending from the coilwindings receiving trench rearward on the rearwardly extending portionof said bottom pole piece and beyond the rear magnetic closure section;an insulating structure having a thin gap defining portion and a thickcoil windings enclosing portion wherein the thin gap defining portion ofsaid insulating structure is formed of predetermined thickness and islocated on the forward wall section of said lateral wall to establishthe thickness of a transducing gap and wherein the thick coil windingsenclosing portion encloses and surrounds that portion of the coilwindings located in the coil windings receiving trench; a top pole piecehaving a front gap section and a rear magnetic closure portion with thefront gap section positioned on the thin gap defining portion of saidinsulating structure and adjacent the front gap section of said bottompole establishing the front end section of said top pole piece as theother side of the transducing gap and with the rear magnetic closureportion thereof contiguous the rearward wall section of said lateralwall establishing a rear magnetic closure portion of said top pole pieceas the other side of a rear magnetic closure section, the bottom surfaceof said top pole piece bridging from the forward wall section to therearward wall section of said lateral wall forming a top enclosure forthe coil windings receiving trench; said top pole piece having acontoured outer surface having a step formed therein and having arearward support section; a leveler layer formed of a material havingsubstantially the same abrading characteristics as that of the top polepiece and having a thickness which is slightly greater than the heightof the step of said top pole piece and having a forward leveler sectionlocated on the front gap section of said top pole piece, and a rearwardleveler section located on a support section positioned a predetermineddistance from and rearward of the forward leveler section of saidleveler layer and rearward of the transducing gap, the forward levelersection and rearward leveler section being adapted to receive andsupport a superstrate attached to said magnetic head by an adhesivemeans substantially located between the forward leveler section and therearward leveler section.
 2. The thin film magnetic head of claim 1further comprisinga superstrate having a relatively planar supportsurface and a tape engaging surface and being formed of a material whichis highly resistive to being abraded by a magnetic media being movedthereacross, and superstrate having the relatively planar supportsurface affixed to the forward leveler section and the rearward levelersection of said leveler layer to enclose the contoured outer surface ofsaid top pole piece layer defining a space located remotely from andrearward of the magnetic transducing gap.
 3. The thin film magnetic headof claim 2 wherein the space between the relatively planar supportsurface of said superstrate and the contoured outer surface of said toppole piece is filled with an adhesive material.
 4. The thin filmmagnetic head of claim 1 wherein said thick coil windings enclosingportion of the insulating structure is an electrically insulatingmaterial which encapsulates that portion of the coil windings located inthe coil windings receiving trench.
 5. A thin film magnetic tape headassembly comprisinga substrate having a depositing surface and an endsurface which is substantially perpendicular to the depositing surface,said substrate being formed of a material which is highly resistive tobeing abraded by a magnetic tape being moved thereacross, said substratehaving a tape engaging surface defined at a predetermined position onthe end surface; a magnetic bottom pole piece layer located on thedepositing surface of said substrate, said bottom pole piece layerhaving a front gap section and a rearwardly extending portion with thefront gap section thereof positioned adjacent the end defining the tapeengaging surface of said substrate and with the rearwardly extendingportion thereof located rearward of and spaced from the front gapsection and the tape engaging surface; a lateral wall layer formed of amagnetic material having a forward wall section and a rearward wallsection defining a coil windings receiving trench therebetween, saidlateral wall layer being formed of predetermined thickness and beingpositioned on said bottom pole piece layer with the forward wall sectioncontiguous the front gap section of said bottom pole piece layerestablishing the forward wall section as one side of a transducing gapand with the rearward wall section being positioned a predetermineddistance rearward from the forward wall section and contiguous therearwardly extending portion of said bottom pole piece forming one sideof a rear magnetic closure section, the coil windings receiving trenchbeing positioned on said bottom pole piece located between forward wallsection and the rearward wall section forming a bottom enclosure for thecoil windings receiving trench; a multiplanar coil having a plurality ofcoil windings formed on said bottom pole piece having a thickness whichis less than the thickness of said lateral wall layer, said multiplanarcoil having a portion of the coil windings located in the coil windingsreceiving trench and the remaining portion thereof extending from thecoil windings receiving trench rearward on the rearwardly extendingportion of said bottom pole piece layer and beyond the rear magneticclosure section; an insulating structure having a thin gap definingsection and a thick coil windings enclosing portion wherein the thin gapdefining portion of said insulating structure is formed of predeterminedthickness and is located on the forward wall section of said lateralwall layer to establish the thickness of a transducing gap and whereinthe thick coil windings enclosing portion encloses and surrounds thatportion of the coil windings located in the coil windings receivingtrench; a magnetic top pole piece layer having a front gap section and arear magnetic closure portion positioned on the thin gap definingportion of said insulating structure and adjacent the front gap sectionof said bottom pole piece establishing the front gap section of said toppole piece layer as the other side of a transducing gap, and with therear magnetic closure portion thereof contiguous the rearward wallsection of said lateral wall layer establishing the rear magneticclosure portion of said top pole piece as the other side of a rearmagnetic closure section, the bottom surface of the top pole piecelayer, bridging from the forward wall section to the rearward wallsection of said lateral wall layer forming a top enclosure for the coilwindings receiving trench; said top pole piece having a contoured outersurface defining a step formed therein and having a rearward supportsection a leveler layer formed of a material having substantially thesame abrading characteristics as that of the top pole piece and having athickness which is slightly greater than the height of the step of saidtop pole piece and having a forward leveler section located on the frontgap section of said top pole piece, and a rearward leveler sectionlocated on a support surface positioned on said top pole piece apredetermined distant from and rearward of the forward leveler sectionof said leveler layer and rearward of the transducing gap, the forwardleveler section and rearward leveler section being adapted to receiveand support a superstrate attached to said magnetic head assembly by anadhesive means substantially located between the forward leveler sectionand the rearward leveler section.
 6. The thin film magnetic head ofclaim 5 further comprisinga superstrate having a relatively planarsupport surface and a tape engaging surface and being formed of amaterial which is highly resistive to being abraded by a magnetic mediabeing moved thereacross, and superstrate having the relatively planarsupport surface affixed to the forward leveler section and the rearwardleveler section of said leveler layer to enclose the contoured outersurface of said top pole piece layer defining a space located remotelyfrom and rearward of the magnetic transducing gap.
 7. The thin filmmagnetic head of claim 6 wherein the space between the relatively planarsupport surface of said superstrate and the contoured outer surface ofsaid top pole piece is filled with an adhesive material.
 8. The thinfilm magnetic head of claim 7 wherein the thick coil windings enclosingportion of said insulating structure is an electrically insulatingmaterial which encapsulates that portion of the multiplanar coilwindings located in the coil windings receiving trench.
 9. The thin filmmagnetic head of claim 8 wherein the relatively planar support surfaceis affixed to the front leveler section and the rear leveler sectionwith a low temperature epoxy.